1. Field of the Invention
The present invention concerns a connection device for random connection of a first number of first transmission/reception units with a second number of second transmission/reception units. The invention also concerns a communication device with at least one first transmission/reception unit and at least one second transmission/reception unit, as well as with a connection device for selective establishment of an electrical connection between the at least one first transmission/reception unit and the at least one second transmission/reception unit. The invention also concerns a method to produce a connection device.
2. Description of the Prior Art
Communication devices to transfer information include at least one first transmission/reception unit as well as at least one second transmission/reception unit. In the simplest case, one of the first transmission/reception units is respectively connected with one of the second transmission/reception units into a channel. In communication devices with multiple transmission channels, a multiplexing method is advantageous with regard to the optimization of costs and the necessary transmission lines. Using such a method, multiple first transmission/reception units can randomly be connected with a second transmission/reception unit, the number of the system components is reduced. In other situations it is necessary to transfer information in parallel between a plurality of first transmission/reception units and a number of second transmission/reception units, and the association of first transmission/reception units and second transmission/reception units must be random. This applies in telephone communication, for example. Such a requirement can be satisfied with a spatial multiplexing method. FIG. 1 shows an arrangement known as a crossbar distribution in a communication device in a schematic presentation. First transmission/reception units are labeled with the reference characters SE1-1, SE2-1, SE3-1 and SE4-1 in FIG. 1. The first transmission/reception units SE1-1, . . . , SE4-1 are coupled with input lines LE1, LE2, LE3, LE4. Second transmission/reception units are labeled with the reference characters SE1-2, SE2-2, SE3-2 and SE4-2 in FIG. 1. The second transmission/reception units SE1-2, . . . , SE4-2 are respectively coupled with an output line LA1, LA2, LA3, LA4. In this exemplary embodiment the number of the first transmission/reception units SE1-1, . . . , SE4-1 is selected corresponding to the number of the second transmission/reception units SE1-2, . . . , SE4-2. This is only an example. The number of the first and second reception units can in principle be selected arbitrarily.
A switching matrix SM is provided for random connection of the first transmission/reception units SE1-1, . . . , SE4-1 and the second transmission/reception units SE1-2, . . . , SE4-2. The switching matrix SM comprises a respective switching element (not shown) at the node points K11, K12, K13, K14, . . . , K41, K42, K43, K44 (in general Kij, wherein i is the number of the input lines and j is the number of the output lines). An electrical connection of the input line and output line intersecting in the node point is thereby effected by a switching element arranged at a node point Kij.
A specific one of the first transmission/reception units SE1-1, . . . , SE4-1 can be electrically connected in parallel with a specific one of the second transmission/reception units SE1-2, . . . , SE4-2 by appropriate activation of respective switching elements by a control circuit (not shown in FIG. 1). This is represented by way of example in FIG. 1 by the communication paths labeled with the reference characters P1, . . . , P4. The first transmission/reception unit SE1-1 is connected with the second transmission/reception unit SE2-2 with the communication path P1. The first transmission/reception unit SE1-1 represents a transmitter and the second transmission/reception unit SE2-2 a receiver, which is indicated by the arrow direction. The electrical connection ensues in that the switching element arranged at the node point K12 is switched to be conductive while the further switching elements in the node points K11, K22, K32 and K42 arranged in the communication path T1 are switched to be blocking.
A communication path P2 between the first transmission/reception unit SE2-1 and the second transmission/reception unit SE1-2, between the first transmission/reception unit S3-1 and the second transmission/reception unit SE302 and between the first transmission/reception unit SE4-1 and the second transmission/reception unit SE4-2 is formed in a corresponding manner. In the shown exemplary embodiment the first transmission/reception units SE2-1 and SE4-1 represent receivers while SE3-1 forms a transmitter. Corresponding to this, the second transmission/reception units SE1-2 and SE4-2 represent transmitters and SE3-2 represents a receiver.
A general requirement of a switching matrix as described in FIG. 1 is that the multiplexing method does not influence the actual signal transmission. The switching elements necessary for the multiplexing possess parasitic elements, a resistor and a capacitor. The capacitor in particular thereby represents an unwanted leak path for high frequencies in the range of more than 100 MHz, which leads to signal losses. A signal integrity problem therefore results, in particular in the transfer of radio-frequency signals.
In order to avoid signal losses, switching elements with low parasitic capacitances have previously been used, or the effect of the parasitic capacitances is actively compensated via corresponding circuit arrangements. Switches with low parasitic capacitances are, for example, PIN diodes that, however, possess the disadvantage of very high initial costs. Although the provision of structural elements to reduce the parasitic capacitances is more cost-effective, it exhibits the disadvantage that the space requirement for the switching matrix rises. The space requirement assumes a magnitude that is no longer tolerable, in particular when switching matrices for random connection possess a large number of first and second transmission/reception units.